FXIIIA or Factor 13A, is a blood and intracellularly produced coagulation factor. This is present in several different cells like platelets, megakaryocytes and fibroblast like messenchymal or histiocytic cells. This can be present in the placenta, uterus and prostate as well as in skin as shown below.

Picture 1 – Factor 13A in use

This antibody is mainly used to assist in differentiation of tumours between dermatofibroma in which has 90% positivity, where as tumours like desmoplastic malignant melanoma are completely negative for this.

Factor 13A has several different applications. Below are a few examples.